Transverse perovskite heterojunction array and preparation method and application thereof

Abstract

The invention discloses a transverse perovskite heterojunction array and a preparation method and application thereof, and relates to the technical field of perovskite material optoelectronic devices. According to the invention, a first perovskite crystal array is prepared on a substrate; preparing a polymer film on the surface of the first perovskite crystal array on one side close to the substrate electrode; and a gas phase replacement method is adopted to prepare the transverse perovskite heterojunction array. Under the assistance of a polymer film, a part of the perovskite array is accurately and efficiently converted into another perovskite by using a gas phase replacement method, so that seamless connection of the two perovskite materials is realized, and a high-quality transverse perovskite heterojunction array is formed. In the optical tuning photoelectric detector prepared based on the heterojunction array, short-wave laser can quickly tune the response capability of a device to long-wave laser, and quick switching of response wavebands is realized; and the development potential and the application value of the perovskite heterojunction photoelectric detector are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite material optoelectronic devices, and in particular to a lateral perovskite heterojunction array and a preparation method and application thereof. Background Art

[0002] Perovskite materials have been widely used in the optoelectronic field due to their simple preparation, flexible and adjustable band gap, and excellent photoconductivity. In order to achieve dual-band or even multi-band detection in the same photodetector, integrating different types of perovskite materials has become an effective strategy to broaden the application range of the detector. However, current narrow-band or multi-band detectors usually exhibit a fixed spectral response and can only detect specific bands. In order to achieve multifunctional integration, some tunable detectors have been designed, usually by changing the bias voltage of the perovskite heterojunction device or adjusting the illumination position to achieve different spectral responses. However, this control method that relies on changing the voltage or illumination position greatly limits the ability to quickly switch between different detection bands. Since light has the advantages of fast propagation and non-contact, using light to control the device can significantly improve the switching speed of the response band.

[0003] Due to the solubility of perovskites, solution methods are often used to prepare vertical perovskite heterostructures. However, this vertical heterostructure will produce severe light loss at the interface of multilayer materials, and at the same time, it places extremely high requirements on the light transmittance of the electrode and the solvent system. In contrast, the lateral device structure allows the photosensitive perovskite material to directly receive light without relying on the light transmittance of the electrode, which is conducive to the development of perovskites in optoelectronic applications. However, the solution method faces severe challenges in the preparation of lateral perovskite heterojunctions, because the preparation process of the second perovskite may dissolve the prepared first perovskite. Due to the soft lattice characteristics of perovskite materials, their internal halide ions can exchange with external halide ions. Using this characteristic, the ion exchange method provides a feasible solution for the preparation of lateral perovskite heterojunctions. However, the existing ion replacement method is mainly used to prepare perovskite crystals with a single gradient band gap, and its application potential in the field of photodetectors has not been fully explored. Therefore, it is of great research significance and application value to develop a simple and efficient perovskite heterojunction preparation method for the preparation of light-tuned lateral perovskite heterojunction photodetectors.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a lateral perovskite heterojunction array and a preparation method and application thereof to solve the above-mentioned technical problems.

[0006] The present invention is achieved in that:

[0007] In a first aspect, an embodiment of the present invention provides a method for preparing a lateral perovskite heterojunction array, which comprises:

[0008] preparing a first perovskite crystal array on a substrate;

[0009] On a side close to the substrate electrode, a polymer film is prepared on the surface of the first perovskite crystal array;

[0010] The lateral perovskite heterojunction array was prepared by gas phase replacement method.

[0011] In a second aspect, an embodiment of the present invention provides a lateral perovskite heterojunction array prepared by the aforementioned preparation method.

[0012] In a third aspect, an embodiment of the present invention provides a light-tuned photodetector based on the aforementioned lateral perovskite heterojunction array.

[0013] In a fourth aspect, an embodiment of the present invention provides a method for preparing the aforementioned optically tunable photodetector, the method comprising:

[0014] An electrode layer is prepared on the side of the lateral perovskite heterojunction array away from the substrate electrode to prepare a light-tuned photodetector;

[0015] The length of the lateral perovskite heterojunction between the electrode layer and the substrate electrode is 400 μm-1600 μm.

[0016] The present invention has the following beneficial effects:

[0017] The embodiment of the present invention prepares a polymer film and a lateral perovskite heterojunction array by using a regional selective gas phase replacement method, thereby overcoming the limitation that the first perovskite crystal may be destroyed when preparing a perovskite heterojunction by a conventional solution method; the effective replacement of the halogen ions of the first perovskite crystal is successfully achieved, and a perovskite heterojunction array with clear boundaries and neat arrangement is formed by using the isolation effect of the polymer film. The polymer film provides a strong guarantee for the preparation and performance optimization of the optically tunable photodetector. The optically tunable photodetector prepared has excellent performance and can quickly switch the response wavelength, which significantly improves the development potential and application value of the perovskite heterojunction photodetector. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 The SEM image of the MAPbBr3 microwire array, the SEM image of a single MAPbBr3 microwire, and the AFM image in Example 1;

[0020] Figure 2 Optical microscope and fluorescence microscope images of the MAPbBr3 micrometer wire array grown at the interface of ITO and glass in Example 1;

[0021] Figure 3 is the lateral MAPbBr3-MAPbBr in Example 1 3-x I x Optical and fluorescence microscopy images of micrometer-wire heterojunction arrays;

[0022] Figure 4 XRD phase diagram of MAPbBr3 crystals after gas phase replacement at different times in Example 1-3;

[0023] Figure 5 is the lateral MAPbBr3-MAPbBr in Example 1 3-x I x Microwire heterojunction, MAPbBr3 and MAPbBr 3-x I x XRD phase diagram of

[0024] Figure 6 is MAPbBr in Example 1 3-x I x , photoluminescence spectra of MAPbBr3 and MAPbI3;

[0025] Figure 7 For the lateral MAPbBr3-MAPbBr in Application Example 1 3-x I x Comparison of the spectral response of the micrometer-wire heterojunction array photodetector without and with 450nm laser irradiation, with 5V external bias applied to the device;

[0026] Figure 8 For the lateral MAPbBr3-MAPbBr in Application Example 1 3-x I x Response time of micrometer-wire heterojunction array photodetector under 450nm laser irradiation;

[0027] Fig. 9 is the lateral MAPbBr3-MAPbBr with different heterojunction lengths in Application Examples 1-3 3-x I x Phototuning properties in a micrometer-wire heterojunction array photodetector: the amplification factor of the 650nm photocurrent by a 450nm laser of the same intensity, with a 5V external bias applied to the device;

[0028] Fig.10 For the optically tuned lateral MAPbBr3-MAPbBr in Application Example 1 3-x I x Schematic diagram of the structure of micrometer-wire heterojunction array photodetector. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0030] In a first aspect, an embodiment of the present invention provides a method for preparing a lateral perovskite heterojunction array, which comprises:

[0031] preparing a first perovskite crystal array on a substrate;

[0032] On a side close to the substrate electrode, a polymer film is prepared on the surface of the first perovskite crystal array;

[0033] The lateral perovskite heterojunction array was prepared by gas phase replacement method.

[0034] It should be noted that the polymer film is a highly light-transmitting film, which is tightly covered on a specific area of ​​the first perovskite crystal array to form an effective isolation barrier, ensuring that the halide ions from the outside can only exchange with the part not covered by the polymer; in order to prepare a perovskite heterojunction array with a clear boundary line, the present invention also uses a thread to block the flow of the polymer solution so that it can be evenly covered on the side close to the substrate electrode. In this process, the concentration of the polymer solution is precisely controlled to ensure that its viscosity is moderate, which can ensure that the thread effectively blocks the flow of the polymer solution and form a polymer film with a clear boundary.

[0035] The regional selective gas phase halogen ion replacement method proposed in the present invention can prepare a lateral perovskite heterojunction array with a good interface lattice match without destroying the original perovskite lattice structure. Specifically, the gas phase replacement method is to perform ion replacement on the side without a polymer film to obtain a second perovskite crystal, and then prepare a lateral perovskite heterojunction array.

[0036] In an optional embodiment of the present invention, before preparing the polymer film, it also includes: placing a linear object on the surface of the first perovskite crystal array and fixing it, and then dripping a polymer solution on the side of the substrate close to the electrode; after the polymer solution completely covers the side of the substrate close to the electrode, removing the linear object, heating it at a temperature of 60°C-120°C to form a film, and obtaining the polymer film.

[0037] Furthermore, the diameter of the wire is 50 μm-200 μm; the wire used in the embodiment of the present invention is made of gold wire, which is soft and can avoid damaging the surface of the first perovskite crystal; in other embodiments of the present invention, wires of other materials can be selected according to actual conditions.

[0038] Specifically, before preparing the polymer film, a high-quality first perovskite crystal array is selected to ensure that its surface is flat and defect-free; a straightened gold wire is gently placed horizontally on the surface of the first perovskite crystal array (placed perpendicular to the array), and the two ends of the gold wire are fixed with tape, so that the first perovskite crystal array is divided into two parts; on the side close to the substrate electrode, a polymer solution is dripped to make it spread evenly to ensure that the first perovskite crystal on this side is completely covered, the gold wire is removed and heated to solidify the polymer solution to form a transparent film, thereby obtaining a polymer film.

[0039] In an optional embodiment of the present invention, the mass concentration of the polymer solution is 0.05 g / mL-0.2 g / mL; further, the polymer is selected from any one of PMMA and PDMS; and the solvent for dissolving the polymer is selected from chlorobenzene or toluene.

[0040] Specifically, the polymer and the corresponding solvent are mixed and uniformly dissolved at 75° C.-85° C. to obtain a transparent polymer solution.

[0041] It should be noted that the concentration of the polymer solution is precisely controlled to ensure that its viscosity is moderate, which can ensure that the gold wire effectively blocks the flow of the polymer solution and form a polymer film with clear boundaries. The specific polymer concentration can be selected from any one of 0.05g / mL, 0.1g / mL, 0.15g / mL and 0.2g / mL, or other values ​​within the range of 0.05g / mL-0.2g / mL.

[0042] In an optional embodiment of the present invention, the structure of the first perovskite crystal is ABX3, wherein A is selected from CH3NH3 + 、CH(NH2)2 + , Cs + and Rb + At least one of, B is selected from Pb 2+ Sn 2+ ,Ge 2+ and Cu 2+ / Cu + At least one of, X is selected from Cl - Br - and I - At least one of .

[0043] It should be noted that the substances used to prepare the precursor solution of the first perovskite crystal are AX and BX or BX2. In the embodiment of the present invention, X is the same halogen ion, and A and B can be reasonably selected according to actual conditions; the solvent used to prepare the precursor solution is at least one of dimethylformamide and dimethyl sulfoxide. The corresponding substances and the solvent are mixed and dissolved evenly at 45°C-55°C until the solution is clear to obtain the first perovskite crystal precursor solution.

[0044] In an optional embodiment of the present invention, the preparation method further comprises:

[0045] Prepare solution: prepare the first perovskite precursor solution and polymer solution for later use.

[0046] Specifically, in an optional embodiment of the present invention, 0.224g CH3NH3Br and 0.734g PbBr2 are added to a mixed solution consisting of 8mL dimethylformamide (DMF) and 2mL dimethyl sulfoxide (DMSO) in proportion, and stirred at 50°C and 500rpm for 12h until the solution is clear to obtain a first perovskite precursor solution. 1g PMMA is added to 10mL chlorobenzene and stirred at 80°C and 500rpm for 12h to obtain a transparent polymer solution. In other embodiments of the present invention, the amount and type of the substances and solvents used in the preparation of the solution can be reasonably adjusted according to actual conditions.

[0047] In an optional embodiment of the present invention, the first perovskite crystal array prepared on the substrate is perpendicular to the electrode of the substrate.

[0048] Furthermore, the substrate has patterned electrodes, the width of the electrodes is 2.5 mm-3.5 mm, and the thickness is 135 nm-165 nm; the material of the substrate is selected from any one of flexible PET, flexible PI, flexible PDMS, hard glass and silicon wafer substrate.

[0049] In an optional embodiment of the present invention, the preparation method further comprises:

[0050] Treating the substrate: cleaning the substrate with acetone, ethanol and deionized water, and drying it; specifically, cleaning the substrate with patterned electrodes having a width of 2.5 mm to 3.5 mm and a thickness of 135 nm to 165 nm with acetone, ethanol and deionized water in turn, and drying it thoroughly.

[0051] It should be noted that the types of electrodes and substrates can be reasonably adjusted according to actual needs. In the embodiment of the present invention, the electrodes are ITO (indium tin oxide) and the substrate is a glass substrate.

[0052] In an optional embodiment of the present invention, the solvent used in the gas phase replacement method is a halide HX', wherein X' is selected from Cl - Br - and I - At least one of; and the elements of X and X' are different.

[0053] It should be noted that the gas phase replacement method of the present invention is a regional selective gas phase halogen ion replacement method, which can prepare a lateral perovskite heterojunction array with a good interface lattice match without destroying the first perovskite lattice structure. This method of directly performing ion replacement on the first perovskite crystal makes the lattice structures of the two perovskites closely connected, which is conducive to the efficient transmission of carriers. It provides the possibility of flexibly adjusting the band gap of the perovskite material, further broadening the application scope of the perovskite material in the optoelectronic field.

[0054] In an optional embodiment of the present invention, a halide solution and a first perovskite crystal array with a polymer film are placed together in a closed container for gas-phase halogen ion replacement, during which heating is performed to volatilize the halide to form a high-concentration halide gas. Due to the diffusion effect caused by the concentration gradient, the halogen ions will enter the first perovskite crystal and gradually replace the original halogen ions to form a second perovskite crystal; while the part covered by the polymer film will not undergo ion replacement due to the isolation effect.

[0055] Specifically, a halide solution different from the halogen ions in the first perovskite crystal is placed in an open glass bottle, and then placed in a larger beaker, and then the bottom of the beaker is covered with absorbent silica gel; the first perovskite crystal array with a polymer film and the substrate are placed in the beaker, the beaker is tightly sealed with tin foil, and the beaker is heated; the perovskite crystal after the replacement is heated and annealed to finally form a lateral perovskite heterojunction array.

[0056] Furthermore, the concentration of the halide is 30wt%-70wt%.

[0057] In an optional embodiment of the present invention, the temperature for preparing the lateral perovskite heterojunction array by the vapor phase replacement method is 30° C.-70° C. and the time is 5 h-20 h.

[0058] It should be noted that if the time is not sufficient for the gas phase replacement method to prepare perovskite heterojunction, the halogen ions in the first perovskite crystal cannot be fully replaced, which will inevitably affect the band structure and electronic properties of the perovskite heterojunction, and thus affect its optical and electrical properties.

[0059] Furthermore, the prepared lateral perovskite heterojunction array is annealed at a temperature of 50°C-70°C and a time of 5min-30min.

[0060] It should be noted that insufficient annealing temperature and time of the lateral perovskite heterojunction array will result in low phase purity of the perovskite material, filled with a large number of defects and impurities, leading to low photoelectric conversion efficiency and affecting the long-term stability of the device.

[0061] In an optional embodiment of the present invention, the preparation method further comprises:

[0062] Template preparation: a micrometer line array pattern is prepared on a silicon wafer, the depth of the pattern is 28 μm-35 μm, and the width is 10 μm-20 μm; PDMS is used for demolding to obtain a PDMS template with the same micrometer line array structure.

[0063] Specifically, the embodiment of the present invention uses inductively coupled plasma etching (ICP) to prepare a micrometer line array pattern on a silicon wafer; the size of the PDMS template is 15×15×5 mm 3 It should be noted that the preparation of the micrometer line array pattern can be selected in other ways according to actual conditions; the size of the template can be selected in other sizes according to actual needs.

[0064] It should be noted that in the embodiments of the present invention, a pattern of a micrometer wire array is prepared to obtain a perovskite heterojunction of a micrometer wire array, which has special significance: on the one hand, the photoresponse current of a single micrometer wire is very small and is not suitable for practical applications; on the other hand, it is difficult to ensure that the ion replacement of each micrometer wire is completely consistent, so the properties of each micrometer wire heterojunction will have certain differences. In order to avoid the influence of such differences, the present invention prepares a micrometer wire array, and multiple micrometer wires are integrated to form a device. The more micrometer wires there are, the more stable the properties of the device.

[0065] In a second aspect, an embodiment of the present invention provides a lateral perovskite heterojunction array prepared by the aforementioned preparation method.

[0066] In a third aspect, an embodiment of the present invention provides a light-tuned photodetector based on the aforementioned lateral perovskite heterojunction array.

[0067] It should be noted that short-wave lasers can tune the device's response to long-wave lasers; light can quickly switch the device's response band.

[0068] In a fourth aspect, an embodiment of the present invention provides a method for preparing the aforementioned optically tunable photodetector, the method comprising:

[0069] An electrode layer is prepared on the side of the lateral perovskite heterojunction array away from the substrate electrode to prepare a light-tuned photodetector;

[0070] The length of the lateral perovskite heterojunction between the electrode layer and the substrate electrode is 400 μm-1600 μm.

[0071] It should be noted that in the lateral perovskite heterojunction array prepared in the embodiment of the present invention, the side close to the substrate electrode, that is, the existing ITO electrode is covered by a polymer film and can be used by scraping off part of the blocking film; therefore, an electrode layer needs to be prepared on the other side of the lateral perovskite heterojunction, corresponding to the ITO electrode on the substrate.

[0072] Specifically, in the embodiment of the present invention, the electrode layer is prepared by evaporation, and the parameters of the evaporation electrode layer are as follows: the vacuum chamber pressure is 3×10 -3 Pa, the heating current of the evaporation tungsten boat is 48A, the heating time is 60s, the width of the electrode layer is 3mm, and the thickness is 100nm. Through the above steps, a perovskite heterojunction device at both ends can be obtained, and the heterojunction length between the electrodes on both sides is 400μm-1600μm, wherein the length of the first perovskite crystal is the same as the length of the second perovskite crystal.

[0073] It should be noted that devices with different lengths of perovskite heterojunctions have different light tuning capabilities under different light intensities.

[0074] In an optional embodiment of the present invention, the material for preparing the electrode layer is selected from any one of Au, Ag, Cu, Al, In, Pt and Cr.

[0075] Furthermore, the thickness of the electrode layer is 70nm-130nm, and the width is 2.5mm-3.5mm; the response capability of the short-wave laser tunable photodetector to the long-wave laser, the wavelength of the short-wave laser is <550nm, and the wavelength of the long-wave laser is >550nm; the time for the optically tunable photodetector to respond to the band switching is ≤350μs.

[0076] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0077] The reagents used in the embodiments of the present invention are as follows: dimethylformamide (DMF) with a purity of 99.9%, dimethyl sulfoxide (DMSO) with a purity of 99.9%, chlorobenzene with a purity of 99.8%, and hydroiodic acid (HI) with a concentration of 55%-58% (wt%). In other embodiments of the present invention, reasonable adjustments can be made according to actual needs.

[0078] Example 1

[0079] This embodiment prepares a lateral perovskite heterojunction array, which includes the following preparation steps:

[0080] (1) Template preparation:

[0081] A micrometer line array pattern was prepared on a silicon wafer by inductively coupled plasma etching (ICP). The depth of the pattern was 32 μm and the width was 20 μm. Then, PDMS was used for demolding to obtain a PDMS template with the same micrometer line array structure. The overall size of the template was 15×15×5 mm. 3 .

[0082] (2) Processing substrate:

[0083] A glass substrate with patterned ITO (indium tin oxide) was selected (the width of the ITO region was 3 mm and the thickness was 150 nm), and the substrate was cleaned with acetone, ethanol and deionized water in sequence and dried thoroughly.

[0084] (3) Preparation of solution:

[0085] 0.224 g CH3NH3Br and 0.734 g PbBr2 were added to a mixed solution consisting of 8 mL dimethylformamide (DMF) and 2 mL dimethyl sulfoxide (DMSO), and stirred at 50 °C and 500 rpm for 12 h until the solution became clear to obtain a precursor solution of MAPbBr3 (the first perovskite); 1 g PMMA was added to 10 mL chlorobenzene and stirred at 80 °C and 500 rpm for 12 h to obtain a transparent polymer solution.

[0086] (4) Preparation of MAPbBr3 micron wire crystal array, i.e., the first perovskite crystal array:

[0087] The specific steps are as follows: transfer the treated substrate and MAPbBr3 precursor solution to a glove box (temperature is 25°C, water and oxygen concentrations are both less than 0.1%); cut the PDMS template to expose both ends of the microstructure channel, stick the side of the PDMS template with the microstructure on the ITO glass substrate, partially covering the ITO electrode, and gently press it to make it fit tightly with the substrate surface; then drop 5μL of MAPbBr3 precursor solution on one side of the PDMS template, and use capillary force to make the solution completely fill the microstructure channel of the template; heat at 60°C to promote the gradual crystallization and extension of MAPbBr3 along the side walls of the microstructure channel; after 1 hour, wait for the solvent to completely evaporate, gently remove the PDMS template to form a continuous and uniform MAPbBr3 micrometer wire crystal array, that is, the first perovskite crystal array.

[0088] (5) Preparation of polymer films in specific areas of the MAPbBr3 micron-wire crystal array:

[0089] The specific steps are as follows: a straightened gold wire (with a diameter of 100 μm) is gently fixed on the surface of the MAPbBr3 microwire array prepared in step (4) (the gold wire is perpendicular to the microwire array) so that it divides the microwire array into two parts; 50 μL of polymer solution is dropped on the substrate on the side with the ITO electrode so that it evenly covers the MAPbBr3 microwire crystal array and the ITO electrode on that side; then the gold wire is gently removed and heated on a hot plate at 90°C for 3 minutes to solidify the polymer solution to form a transparent film, i.e., a polymer film.

[0090] (6) Preparation of lateral MAPbBr3-MAPbBr 3-x I x Microwire Heterojunction Arrays:

[0091] The specific steps are as follows: 1 mL of HI solution is dripped into an open 10 mL glass bottle, and the bottle is placed in a 50 mL beaker, and the bottom of the beaker is covered with absorbent silica gel; the polymer film prepared in (5) together with the substrate is placed in the bottom of the beaker, the beaker is tightly sealed with tin foil, and heated on a hot plate at 48 °C for 15 h; the HI in the glass bottle is volatilized by heat, and a high concentration of HI gas is formed in the beaker. Due to the diffusion effect caused by the concentration gradient, the iodide ions enter MAPbBr3 and gradually replace the original bromide ions to form MAPbBr 3-x I x ; The covered MAPbBr3 part will not undergo ion replacement due to the isolation effect of the polymer film; after the replacement is completed, the perovskite crystal is heated on a hot plate at 60°C for 15 minutes for annealing, and finally a seamless lateral MAPbBr3-MAPbBr 3-x I x Microwire heterojunction array, i.e. lateral perovskite heterojunction array.

[0092] Example 2

[0093] This embodiment prepares a lateral perovskite heterojunction array, and the preparation steps thereof differ from those of the embodiment 1 only in that:

[0094] (6) Preparation of lateral MAPbBr3-MAPbBr 3-x I x Microwire Heterojunction Arrays:

[0095] The polymer film prepared in (5) together with the substrate was placed at the bottom of a beaker, the beaker was tightly sealed with tin foil, and heated on a hot plate at 48°C for 10 h.

[0096] Example 3

[0097] This embodiment prepares a lateral perovskite heterojunction array, and the preparation steps thereof differ from those of the embodiment 1 only in that:

[0098] (6) Preparation of lateral MAPbBr3-MAPbBr 3-x I x Microwire Heterojunction Arrays:

[0099] The polymer film prepared in (5) together with the substrate was placed at the bottom of a beaker, the beaker was tightly sealed with tin foil, and heated on a hot plate at 48°C for 5 h.

[0100] Application Example 1

[0101] This application example provides a light-tuned photodetector based on a lateral perovskite heterojunction array, which includes the following preparation steps:

[0102] The lateral MAPbBr3-MAPbBr prepared in Example 1 3-x I x Micrometer-wire heterojunction arrays are used to prepare light-tuned photodetectors; the existing ITO electrode on one side of MAPbBr3 (i.e., the first perovskite crystal side) is covered with a PMMA film, which can be used by scraping off part of the blocked film; therefore, it is necessary to 3-x I x An electrode layer is evaporated on one side, corresponding to the ITO electrode on the substrate.

[0103] In this application example, Au electrodes are evaporated and the vacuum chamber pressure is 3×10 -3 Pa, the heating current of the evaporation tungsten boat is 48A, the heating time is 60s, the width of the Au electrode layer is 3mm, and the thickness is 100nm. Through the above steps, a perovskite heterojunction device at both ends can be obtained, that is, a light-tuned photodetector. The structural schematic diagram is shown in Fig.10 .

[0104] The length of the perovskite heterojunction between the electrodes on both sides is 400 μm, where MAPbBr3 and MAPbBr 3-x I x The same length.

[0105] Application Example 2

[0106] This application example provides a light-tuned photodetector based on a lateral perovskite heterojunction array. The preparation steps thereof are different from those of application example 1 only in that:

[0107] The length of the perovskite heterojunction between the electrodes on both sides is 800 μm, where MAPbBr3 and MAPbBr 3-x I x The same length.

[0108] Application Example 3

[0109] This application example provides a light-tuned photodetector based on a lateral perovskite heterojunction array. The preparation steps thereof are different from those of application example 1 only in that:

[0110] The length of the perovskite heterojunction between the electrodes on both sides is 1600 μm, where MAPbBr3 and MAPbBr 3-x I x The same length.

[0111] Test Example 1

[0112] In this test example, the MAPbBr3 micron wire crystal prepared in Example 1 was observed by SEM, AFM, optical microscope and fluorescence microscope; 3-x I x The micrometer-wire heterojunction was observed by optical microscopy and fluorescence microscopy.

[0113] The SEM and AFM observations of MAPbBr3 micron wire crystals were performed by Zeiss Sigma FE-SEM and Bruker Dimension Icon, respectively. Figure 1 MAPbBr3 micron wire crystals were observed by optical microscopy and fluorescence microscopy using Zeiss AxioCam ICC 5. Figure 2 ;MAPbBr3-MAPbBr 3-x I x The observation results of microwire heterojunction are shown in Figure 3 .

[0114] It should be noted that the MAPbBr3 micrometer wire crystal arrays prepared in Examples 1-3 have the same preparation processes and corresponding parameters, and the pictures taken in Example 1 are used as an example for description.

[0115] from Figure 1 It can be seen that the MAPbBr3 micron wire crystal array exhibits a continuous and uniform morphology. The width of each micron wire is about 1.35 μm and the thickness is about 600 nm. The micron wire remains continuous at the boundary between the ITO and glass substrate.

[0116] from Figure 2 It can be seen that the MAPbBr3 micron wire crystal array has no obvious breakage phenomenon and emits uniform and bright fluorescence under a fluorescence microscope.

[0117] from Figure 3 It can be seen that after the gas phase halogen ion replacement is completed, optical microscope observation shows that MAPbBr3 changes from its original yellow color to MAPbBr 3-x I xof black; from the fluorescence luminescence, the micron-wire heterojunction array is neatly arranged with clear boundaries.

[0118] Test Example 2

[0119] In this test example, the MAPbBr3 micron wire crystals prepared after gas phase halogen ion replacement at different times in Examples 1-3 were subjected to XRD phase analysis. The relevant instrument was Rigaku Smartlab. The results are shown in Figure 4 MAPbBr3-MAPbBr prepared in Example 1 3-x I x Microwire heterojunction, MAPbBr3 and MAPbBr 3-x I x XRD phase analysis results are shown in Figure 5 .

[0120] from Figure 4 It can be seen that the ion replacement in Example 3 was not successful, because the diffraction peaks of the MAPbBr3 crystals after replacement were basically consistent with those before replacement; however, the image of the MAPbBr3 crystals after ion replacement in Example 1-2 formed an obvious broad peak on the right side of the original peak, which corresponds to the MAPbBr 3-x I x The diffraction peaks of ions indicate the success of ion replacement.

[0121] from Figure 5 It can be seen that in Example 1, MAPbBr3-MAPbBr 3-x I x XRD phase diagram of the microwire heterojunction, which contains both MAPbBr3 and MAPbBr 3-x I x The diffraction peaks of MAPbBr3-MAPbBr 3-x I x Successful preparation of heterojunction.

[0122] Test Example 3

[0123] This test example is to prepare MAPbBr3 micron wire crystals, MAPbBr3-MAPbBr 3-x I x Micrometer wire and MAPbI3 were tested for photoluminescence spectroscopy using the HORIBALabRAM HR Evolution instrument. Figure 6 .

[0124] from Figure 6 It can be seen that MAPbBr in Example 1 3-x I xThe emission peak of is significantly shifted compared to that of MAPbBr3 and is close to that of MAPbI3, which further proves the success of ion replacement.

[0125] Test Example 4

[0126] This test example studies the photoelectric properties of the photodetector based on the lateral perovskite heterojunction array prepared in Application Examples 1-3, as follows:

[0127] The test was conducted using a semiconductor analyzer (Keysight B1500A). The light sources were 450nm and 650nm monochromatic lasers with adjustable frequencies. The maximum powers of the two lasers were 108.4mW / cm 2 and 153.0mW / cm 2 The spectral response is achieved by dividing a 150W xenon lamp light source into monochromatic lights with a spacing of 5nm through a monochromator, which are then irradiated to the effective area of ​​the device one by one. The generated photocurrent is collected by the electrode, amplified by the pre-signal amplifier (Stanford SR570), and then collected by the phase-locked amplifier (Stanford SR830). The bias voltage is directly provided by the pre-signal amplifier.

[0128] The relevant results are as follows: The spectral response curve of the optically tunable photodetector in Application Example 1 is as follows: Figure 7 As shown (it should be noted that the 450nm laser intensity is close to the monochromatic light intensity produced by the monochromator); the result of the response time of the optically tunable photodetector to the 450nm laser in Application Example 1 is shown in Figure 8 The results of the optical tuning performance test of the optically tunable photodetector prepared in Application Examples 1-3 are shown in Fig. 9 .

[0129] from Figure 7 It can be seen that the optically tunable photodetector only responds to short-wave lasers. However, when a 450nm laser is used to irradiate the device, the device's response to long-wave lasers is enhanced. This indicates that the 450nm laser can enhance the device's response to long-wave lasers, showing the properties of the optically tuned response band.

[0130] from Figure 8 It can be seen that the response time of the optically tunable photodetector to 450 nm laser is about 350 μs, which further highlights its capability of fast optical tuning.

[0131] from Fig. 9It can be seen that for 450nm and 650nm lasers of the same intensity, the relationship between the multiple of the 650nm photocurrent of the optically tuned photodetectors with different heterojunction lengths amplified by the 450nm laser and the light intensity; it can be seen that the photodetector with a longer heterojunction has a greater amplification in the low light intensity area, but is relatively small in the high light intensity area. In contrast, the optically tuned photodetector with a shorter heterojunction length in Application Example 1 has the largest amplification in the high light intensity area, even up to 1000 times. This excellent optical tuning characteristic is mainly due to the excellent photoconductivity of the perovskite material and the successful realization of the lateral perovskite heterojunction array in the present invention.

[0132] In summary, a lateral perovskite heterojunction array and a light-tuned photodetector based on the lateral perovskite heterojunction array prepared in the embodiments of the present invention have the following characteristics:

[0133] (1) The present invention utilizes a regioselective gas-phase halogen ion replacement method to prepare a lateral perovskite heterojunction array, and utilizes the isolation effect of a polymer film to successfully prepare a perovskite heterojunction array with clear boundaries and neat arrangement, which provides a strong guarantee for subsequent device preparation and performance optimization.

[0134] (2) The present invention utilizes a regioselective gas-phase halogen ion replacement method to prepare a lateral perovskite heterojunction array, successfully achieving effective replacement of halogen ions in the first perovskite crystal to form a second perovskite crystal; effectively avoiding the destruction of the prepared first perovskite crystal, and overcoming the limitation that the preparation of the second perovskite in the traditional solution method may destroy the original perovskite;

[0135] Since the second perovskite is formed by ion replacement on the basis of the first perovskite crystal, the lattice structures of the two perovskites are closely connected, which is conducive to the efficient transmission of carriers. This method of direct replacement on the original perovskite crystal provides the possibility of flexible adjustment of the band gap of the perovskite material, further broadening the application range of perovskite materials in the optoelectronic field.

[0136] (3) The present invention utilizes a regioselective gas-phase halogen ion replacement method to prepare a lateral perovskite heterojunction array. Based on the heterojunction array, a lateral perovskite photodetector with excellent optical tuning performance and rapid switching of response wavelength is successfully realized, which significantly improves the development potential and application value of perovskite heterojunction photodetectors.

[0137] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a lateral perovskite heterojunction array, characterized in that: The preparation method comprises: preparing a first perovskite crystal array on a substrate; On the side close to the substrate electrode, a polymer film is prepared on the surface of the first perovskite crystal array; The lateral perovskite heterojunction array was prepared by gas phase replacement method.

2. The preparation method according to claim 1, characterized in that: Before preparing the polymer film, the method further includes: placing a linear object on the surface of the first perovskite crystal array and fixing it, and then dripping a polymer solution on a side of the substrate close to the electrode; After the polymer solution completely covers the side of the substrate close to the electrode, the thread-like object is removed, and the polymer film is obtained by heating at a temperature of 60°C to 120°C to form a film; Preferably, the diameter of the thread-like object is 50 μm-200 μm; Preferably, the mass concentration of the polymer solution is 0.05 g / mL-0.2 g / mL; Preferably, the polymer is selected from any one of PMMA and PDMS; Preferably, the solvent for dissolving the polymer is selected from chlorobenzene or toluene.

3. The preparation method according to claim 1, characterized in that: The structure of the first perovskite crystal is ABX3, where A is selected from CH3NH3 + 、CH(NH2)2 + , Cs + and Rb + At least one of, B is selected from Pb 2+ Sn 2+ ,Ge 2+ and Cu 2+ / Cu + At least one of, X is selected from Cl - Br - and I - At least one of; Preferably, the first perovskite crystal array prepared on the substrate is perpendicular to the electrode of the substrate; Preferably, the substrate carries a patterned electrode, the electrode has a width of 2.5 mm to 3.5 mm and a thickness of 135 nm to 165 nm; Preferably, the material of the substrate is selected from any one of flexible PET, flexible PI, flexible PDMS, hard glass and silicon wafer substrate.

4. The preparation method according to claim 1, characterized in that: The solution used in the gas phase replacement method is a halide HX', wherein X' is selected from Cl - Br - and I - At least one of; and the elements of X and X' are different; Preferably, the concentration of the halide is 30 wt% to 70 wt%.

5. The preparation method according to claim 1, characterized in that: The temperature for preparing the lateral perovskite heterojunction array by the gas phase replacement method is 30°C-70°C and the time is 5h-20h; Preferably, the prepared lateral perovskite heterojunction array is annealed at a temperature of 50° C. to 70° C. for a time of 5 min to 30 min.

6. The preparation method according to claim 1, characterized in that: The preparation method further comprises: Preparing a template: preparing a micrometer line array pattern on a silicon wafer, the depth of the pattern being 28 μm-35 μm and the width being 10 μm-20 μm; performing a demolding process using PDMS to obtain a PDMS template having the same micrometer line array structure; Treat the substrate: clean the substrate with acetone, ethanol and deionized water, and dry it; Prepare solution: prepare the first perovskite precursor solution and polymer solution and set them aside.

7. A lateral perovskite heterojunction array prepared by the preparation method according to any one of claims 1 to 6.

8. A light-tuned photodetector based on the lateral perovskite heterojunction array as claimed in claim 7.

9. A method for preparing the optically tunable photodetector according to claim 8, characterized in that: The preparation method comprises: An electrode layer is prepared on the side of the lateral perovskite heterojunction array away from the substrate electrode to prepare a light-tuned photodetector; The length of the lateral perovskite heterojunction between the electrode layer and the substrate electrode is 400 μm-1600 μm.

10. The method for preparing a light-tuned photodetector according to claim 9, characterized in that: The material for preparing the electrode layer is selected from any one of Au, Ag, Cu, Al, In, Pt and Cr; Preferably, the electrode layer has a thickness of 70 nm to 130 nm and a width of 2.5 mm to 3.5 mm; Preferably, the short-wave laser can tune the response capability of the optically tuned photodetector to the long-wave laser, the wavelength of the short-wave laser is <550nm, and the wavelength of the long-wave laser is >550nm; The time for the optical tuning photodetector to respond to band switching is ≤350 μs.

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